Update tests for Rails 4.2, Ruby 2.2

+Fix Rails 3.2 gemfile for Ruby 1.8
+remove Rails 4.0 test
+Update Rails 4.2 version
+Remove 2.0 tests, replace w/2.2
Merge pull request #273 from nateberkopec/update-rails-gemfiles

Fix Rails 3.2 gemfile for Ruby 1.8, remove Rails 4.0 test